易货经济依赖具有互利需求的贸易伙伴来达成协议。例如，农民A可能有一个生产性的鸡舍但没有奶牛，而农民B有几头奶牛但没有鸡舍。这两个农民可能会同意定期交换这么多鸡蛋以获得如此多的牛奶。经济学家将此称为双重巧合 – “双重”，因为有两个政党和“需要的巧合”，因为双方都有完美匹配的互惠需求。 W.S. 19世纪的英国经济学家杰文斯创造了这个术语，并解释说这是易货交易的一个固有缺陷：“物物交换的第一个困难是找到两个人，他们的一次性财产相互适合彼此的需要。可能有很多人想要，并且许多人拥有那些想要的东西;但是为了允许一个易货行为必须有一个双重巧合，这很少会发生。“欲望的双重巧合有时也被称为欲望的双重巧合。虽然找到牛奶和鸡蛋等主要贸易伙伴可能相对容易，但大型复杂的经济体充满了利基产品。 AmosWEB提供了一个生产艺术设计伞架的人的例子。这种伞架的市场可能是有限的，为了与这些架子中的一个进行易货，艺术家首先需要找到想要一个人的人，然后希望这个人具有艺术家愿意接受的同等价值的东西。
The barter economy relies on trading partners with mutually beneficial needs to reach an agreement. For example, Farmer A may have a productive chicken house but no cows, while Farmer B has several cows but no chicken houses. The two farmers may agree to exchange so many eggs on a regular basis to get so much milk. Economists call this a double coincidence – “dual” because there are two parties and “coincidence of need” because both parties have perfectly matched reciprocal needs. WS 19th century British economist Jevons coined the term and explained that this is an inherent flaw in barter transactions: “The first difficulty in bartering is to find two people whose one-time property fits each other. The needs of each other. There may be many people wanting, and many people have what they want; but in order to allow a barter behavior must have a double coincidence, this rarely happens. “The double coincidence of desire is sometimes called The double coincidence of desire. While it may be relatively easy to find major trading partners such as milk and eggs, large and complex economies are full of niche products. AmosWEB provides an example of a person who produces an art design umbrella stand. The market for such umbrella stands may be limited. In order to barter with one of these shelves, the artist first needs to find someone who wants a person and then hopes that the person has something of equal value that the artist is willing to accept.